As a test for the knowledge you have gained in the thorax, examine radiographs of the thorax. There are two main views that are generally examined:

Another view frequently taken is the left or right obliques.

For this lesson, we will only show the PA and Lateral views.

In a PA view, the anterior chest is placed forward onto a film holder. The x-ray machine then shoots x-rays through the body and onto the film. In this way, the anterior thoracic structures should have the best resolution. Most of you have had a general PA radiograph taken. Remember that they always have you take in a deep breath and hold it and also to place you hands on your hips with your shoulders pressed against the film. What this does is to pull the thorax as far forward as possible and the air in the lungs will give a better contrast to muscular structures and viscera because it will be black.

Identify the following structures:

  • scapula
  • coracoid process
  • clavicle
  • trachea (TR)
  • aortic arch (AA)
  • right auricle (RAu)
  • left primary bronchus (LPB)
  • right border of the heart (RB). Remember that the right atrium forms this border.
  • pulmonary vessels (PV)
  • descending aorta (DA)
  • left border of the heart (LB) formed by the left ventricle (LV)
  • right diaphragm (RD) Usually slightly higher that the left diaphragm (LD)
  • vertebral spine (VS)
  • 12th rib
  • lower border of the breast in the female (BR)
  • gas bubble in the stomach (usually gives a clue to where the stomach is
The lateral view gives a different appearance to the shadow of the heart and aorta.


  • scapula
  • breast (BR) if a female
  • right ventricle (RV)
  • left atrium (LA)
  • primary bronchi (B)
  • ascending aorta (AsA)
  • aortic arch (AA)
  • left and right diaphragms
  • gas bubble (gb) in the stomach. Since the stomach is on the left side of the body, it should also be under the left diaphragm. From the lateral view, the right diaphragm is not always higher than the left.
  • bodies of the vertebrae (VB)
  • intervertebral space (IVS)
  • intervertebral foramen (IVF)
  • ribs
Respiration   Cross Sections of the Thorax

Table of Contents for Thorax Practice Examination